William l



(No Model.)

W. L. VOELKER.`

INCANDESGENTELEGTRIG LAMP.

No. 255,219. Y Patentedmar. 21.1882.

JL .Jf-

Mmeseany Ilm/edm# .UNITED STATES-h PATENT OFFICE.

WILLIAM L. voELKEn, on MoEro-N, PENNSYLVANIA, AssIGNon To JOHN H..InwlIN, TRUSTEE, on sAMEPLAoE.

iNeAN DESCENT ELEcrRlc LAMP.

SPCIFICATION'formng part of Letters :Patenti N0. 255,219, dated March 21, 1882. n 4 Application tiled December 135, 1881. (No model.) l

To all whom it may concern:

Be it known that I, WILLIAM L. VOELKEE, ot'Morton,in the county ofDelaware and State of Pennsylvania, have invented certain new and useful Improvements in Incandescent Electrie Lamps, of which' the following is a full, clear', and exact description, reference being had to the accompanying drawing and the letters 0i' reference marked thereon. v e My invention relates especially to the construction of incandescent electric lamps of the class known as vacuum/and has lor its object the production of a completed lamp in -which the vacuum is perlector as nearly so as can' possibly be attained.

It consists essentially in forming the bulb which constitutes the wall of the completed f lamp with an elongated section'of tubing attached to its upper extremity,'said tubing being so constructed and arran'ged as to contain certain chemicals used in forming a high vacuum,aud incertain novel methods of construction and manipulation, all of .which will be hereinafter first fully described, and then pointed out in the.claims. f A The drawing herewith presented illustrates the method of construction employed by mein myimpro'ved lamp. v Heretofore greatdifculty has been experienced in obtaining a perfect vacuum in the i construction of electric lamps, as bythe ordinary method o f sealing the .bulb after exhaustion with `the pump someair will be admitted during the process. The presence of moisture, in lamps thus constructed 'has also been a source of great annoyance. To overcome these diiculties is the object of my'invention. In' the drawing, A isl the glass bulbot the lamp, formed inthe usual manner.-

4o B is'the filament of carbon, soldered to the'.

' copp'er'conductors D,extending through amass einen-conducting material, E, seated in the tiibe A' at the neck of the bulb.: Beforereach- A `ing the extremity of tube A the copper con- 4 5 ductors are secured to platinum connections D',

extending through the sealed portion of theq tube. ,Tube A' is made solid at A2 for about one-half an inch, as indicated.

H is a small bulb attached to the extremity of bulb A, with by means of the small tube I. Bulb H contains hydrate of potassa L. 'lo bulb H is attached a second small bulb, H', communicating with H by means of small tube I. Said bulb H' contains broken puInice-stone L', sat- 5 5 urated.\vith sulphuric acid.

In the drawing the lamp is shown in an inverted position, as it is so supported while completing the vacuum. When 4the lamp is completed, ready for exhaustion, it is charged 6o with pure carbonio-acid gas. It is then 0xhausted to the highest possible degree attainable with a mercurial pump, after which the rarcfaetion is continued still further by the aid of hydrate of potassa in tbeman ner well known 6 and understood by chemists and others skilled in the art to which myinvention relates. When th'e exhaustion is compl teV the lamp is sealed at a. It is then connecter with an electric gen-v erator and the carbon lament heated 'to a low 7o red heat, the heat being gradually increased until the filament isincandescent. By this means l the aqueous vapor contained in the pores oftheI carbon is expelled without decomposition, and

-is finally absorbedby the sulphuric ,acidwith 75 which the pumice-stone issaturated,the slight residue of carbonicacid contained in thelamp being gradually absorbed by the hydrate of potassa. Traces of oxygen existinginthelamp, f ,combining .with the carbon at white heat, forml 8o carbonio acid, and also with the hydrogen (ever present in carbon) to form water, both of which are absorbed by the before-mentioned ehemie cals. 1t will thusbe seen thatv a vacuum is attained thatl in thepresent state of the, art 85 maybe considered as absolutely perfect.

' -After the above chemical reactions are considered complete the lamp is finally sealed at I, and is ready for permanent use.

Having now what I cla-im as new therein, and desire to secure'by Letters Patent, is

Y 1. The herein-'described method of attaining 'a perfect vacuum inincandescent electric lamps-that 1s to say, by forming the main 95g bulb of the lamp with two small .bulbs having `free communication with said main bulb. containing the incandescing lament of carbon,

and having communication there- 5o fully described my invention, -9o l 2.' The main bulb A, incandescing filamentvof carbon B, connections D 1)',` bulb H for holdinghydrate of potassa., and bulb H' for and removing the small bulbs, subl holding pumice-stonc saturatedwrithsulphuric acid, the whole combined and arranged to operate substantially as shown and described.

In testimony that I claim the foregoing I 15 have hereunto set my hand in the presencev of y two witnesses.

; WILLIAM L. VOELKER.'

W illnesses:

SAMUEL BELL, J. M. GAUN, J r. 

